Integrated circuit power supply

ABSTRACT

An integrated circuit system includes a substrate of an electrical insulating material having a surface. Mounted on the surface of the substrate is an IC, a semiconductor piece having therein a circuit, such as a microprocessor, having a plurality of functional blocks. Also mounted on the substrate are a plurality of power supply chips. Each of the power supply chips is connected through conductors and vias in the substrate to a separate functional block on the IC semiconductor piece. Each of the power supply chips forms part of a circuit, such as a DC-DC converter, which is capable of reducing a voltage supplied thereto to a lower voltage suitable for the particular functional block to which the particular power supply chip is connected. Thus, a single relatively large voltage fed to the power supply chips through conductors on the substrate is reduced by each power supply chip to a lower voltage suitable for the particular functional block of the IC semiconductor piece.

This application claims the benefit of U.S. Provisional ApplicationSerial No. 60/108,077 filed Nov. 12, 1998, and U.S. ProvisionalApplication Serial No. 60/117,908 filed Jan. 29, 1999.

FIELD OF THE INVENTION

The present invention relates to an integrated circuit (IC) powersupply, and, more particularly, to a semiconductor integrated circuitsystem which includes a plurality of power supplies contained within thesystem which are electrically connected to different parts of thecircuit within the system.

BACKGROUND OF THE INVENTION

Semiconductor integrated circuit devices are getting larger because theyincorporate a number of various types of circuits on a single chip. Inorder to accommodate all of the various circuits on a single chip, thefeature size of the various elements forming the circuit are becomingsmaller. Thus, the feature size of these integrated circuits are scalinginto the deep submicron range. For such sizes, the power supply voltagesare reaching towards the sub-one volt level, and clock speeds arescheduled to exceed one Gigahertz. For very large integrated circuits,such as a microprocessor, the power supply current is expected to bemany tens of amperes. To provide this type of power from off chip isvery difficult and requires a large number of power and ground pads(ports) around the chip. Also, distributing the current on chip from thelarge number of power and ground pads requires many relatively wide andthick metal conductors to prevent the significant high resistance losseswhich could ultimately limit the device performance.

SUMMARY OF THE INVENTION

An integrated circuit device includes a substrate of an insulatingmaterial having a surface. An IC semiconductor chip is mounted on thesurface of the substrate. The IC chip contains an electrical circuithaving a plurality of functional blocks. A plurality of power supplychips are mounted on the substrate with the power supply chips beingelectrically connected to separate functional blocks of the IC chip.Each of the power supply chips is capable of reducing an input voltageto a lower voltage as required by the functional block to which thepower supply chip is connected.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic sectional view of a form of the integrated circuitsystem of the present invention;

FIG. 2 is an enlarged sectional view of the circled portion of theintegrated circuit system shown in FIG. 1; and

FIG. 3 is a schematic sectional view of a sealed package including theintegrated circuit system of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

Referring initially to FIG. 1, the integrated circuit system of thepresent invention is generally designated as 10. Integrated circuitsystem 10 comprises a substrate 12 of a body 14 of an insulatingmaterial, such as a ceramic, on a base 16 of a conductive material, suchas a metal. The insulating body 14 can be formed of a plurality oflayers of the insulating material which are bonded together, the body 14being bonded to the metal base 16. The body 14 may also include metalcircuitry 18 screen printed onto the surface of each of the insulatinglayers 14, Conductive vias 20 formed in the layers 14 are filled withconductive material to connect the various circuits 18 on the layers 14.These vias 20 extend through the body 14, connecting the variousconductors 18 to the top surface 22 of the body 14.

The above substrates are known as multilayer ceramic printed circuitboards. They are made from low firing temperature glasses thatcrystallize below about 950° C. Such glasses include those of thecordierite-forsterite type made from oxides of magnesium, aluminum andsilicon. A green tape composition is made from finely divided glassparticles, optionally including other inorganic filler particles, mixedwith an organic vehicle to form a slip or slurry. The slip is cast inthe form of a tape, called green tape. The tape is dried and then firedto form a ceramic layer.

Conductive circuits can be applied to the surface of the green tape byscreen printing a conductor ink, made of conductive particles, such asof copper, silver or gold, glass particles, generally of the same glassas that used to make the green tape, and an organic vehicle. Vias areformed in the green tape which are filled with a conductive via ink,generally also made of a glass which can be the same as that used tomake the green tape or a higher Tg glass, a conductive powder and anorganic vehicle. The conductive vias electrically connect the screenprinted circuits. A plurality of the screen printed green tapes are thenaligned, laminated together and fired to remove the organic materialsand crystallize the glass.

A recent development has been the addition of a metal support substratebonded to the bottom of the green tape stack. Such metal supports addmechanical strength to the green tape stack. Further, when a suitablebonding glass is used to bond the green tape stack to the metal supportsubstrate, the metal support prevents shrinkage in the x and ydimensions, so that all of the shrinkage is found in the z, or thicknessdimension. This permits closer tolerances in the circuitry and anypassive components included within the green tape stack.

The metal support can be made of copper clad molybdenum, or copper cladKovar® alloy. Kovar® is a registered trademark of Carpenter Technologyfor an alloy of iron, nickel, cobalt and a minor amount of manganese.The bonding glass can be screen printed onto the metal supportsubstrate, and generally has a coefficient of expansion higher than themetal support substrate and the glass of the green tape. The bondingglass can comprise, in % by weight, about 45-55% of zinc oxide, from30-40% of boron oxide, from 3-7% of calcium oxide and from 3-7% ofalumina, or 20-45% of barium oxide, 5-15% of calcium oxide, 15-22% ofzinc oxide, 15-25% of silicon oxide and 15-25% of boron oxide.

Glass compositions compatible with Kovar® include crystallizableZnO—MgO—B₂O₃mixtures. These glasses can also include non-crystallizablelead-based glasses or oxide-based fillers.

The green tape stack can be made with punched cavities, into whichpassive devices can be placed; however, more conveniently, devices suchas capacitors, resistors, inductors and the like can be screen printedonto a green tape stack. The manufacture of such passive devices will befurther explained below.

As shown in FIG. 1, the body 14 has a plurality of spaced recesses 24formed in its top surface 22. As more clearly shown in FIG. 2, each ofthe recesses 24 exposes a portion of a conductor 18 at the bottom of therecess 24. Also, as shown in FIG. 2, the body 14 may have areas 26 of amagnetic material having conductors 28 either surrounding (not shown) orembedded therein to form inductors or the like.

Over the top surface 22 of the body 14 is an IC piece 30. The IC piece30 comprises a semiconductor material 38, such as silicon, havingtherein transistors, diodes, resistors and capacitors which areconnected together to form a desired circuit or a series of circuits,such as a microprocessor and related circuitry. The structure of such ICcircuits are well known and will not be described in detail. However,the terminal pads for the various parts of the circuits extend to thesurface of the base 16 and terminal bumps 32, of a conductive materialsuch as a metal, are formed on each of the terminal pads .It should beunderstood that instead of terminal bumps 32, any other well known typeof surface mountable terminal may be used at each of the terminal pads.The IC chip 30 is mounted on the substrate 12 with the terminal bumps 32being seated on the top surface 22 of the body 14, As shown in bothFIGS. 1 and 2, each of the terminal bumps 32 is seated directly on thetop of a conductive via 20 and is bonded thereto, such as by welding orsoldering. Thus, the circuits in the IC piece 30 are electricallyconnected to the conductors 18 in the body 14 through the terminal bumps32 and the vias 20. If desired, a conductive terminal area (not shown)may be provided on the top surface 22 of the body 14 around and overeach of the vias 20 so as to simplify making the electrical connectionof the terminal bumps 32 to the vias 20.

A separate power supply circuit chip 34 is mounted in each of therecesses 24 in the body 14 of the substrate 12. Each of the power supplyCircuit chips 34 is an integrated circuit which comprises a chip of asemiconductor material having various circuit elements, such astransistors, diodes, resistors and capacitors therein to form thedesired circuit. The circuit for each of the power supply circuit chips34 is preferably a DC-DC converter to convert the high voltage suppliedto the integrated circuit system 10 to a lower voltage suitable for theparticular part of the main circuit to which the power supply circuit 34is connected. As shown in FIG. 2, each of the power supply circuit chips34 may be electrically connected to its respective portion of thecircuit on the IC piece 30 by a wire bond 36. The wire bond 36 extendsfrom the power supply circuit chip 34 to a conductor 18 which is exposedat the bottom of the recess 24. However, if desired, the power supplycircuit chip 34 may be electrically connected to the conductors 18 byany other well known type of connection, such as a surface bond. Thus,each of the power supply circuit chips 34 is designed to reduce thelarger input voltage to a lower voltage which is required for theparticular part of the integrated circuit on the IC chip 30. Thereby,although a single relatively high voltage may be supplied to the system10, each portion of the integrated circuit is supplied with only thelower voltage which is required for that particular portion of thecircuit. In addition, the connections between the IC chip 30 and thepower supply circuit chips 34 are made using vias directly connected tothat section on the IC piece 30 where power is needed, rather than topads located on the perimeter of the chip as in a prior art chip. Thiskeeps the power bus widths narrow and the lengths on the IC piece 30short, with acceptable power bus thickness, while saving space andminimizing resistive current loss and electrical noise. Also, the commonsignal ground on the IC piece 30 takes minimal current, and can be ofminimum width. Alternatively, a differential drive could be used betweenfunctional blocks, allowing some difference in the common signalreference bus voltage without affecting signal integrity. In yet anotherembodiment, the control of the power supply circuit chips 34 can befabricated on separate chips to the power supply switching devices, or acommon control chip can be used to control several output switchingdevices.

If desired, additional capacitors, inductors, transformers and resistorsmay be fabricated or mounted on the surface of the IC piece 30 or thepower circuit chip 34. Also, such devices can be fabricated within thelayers of the insulating body 14 of the substrate 12. Power supplyenergy storage capacitors may be formed on the surface of the IC piece30 for maximum performance. In addition, feedback lines may be providedfrom the IC piece 30 to the power supply circuit chips 34 to providebetter regulation.

Referring to FIG. 3, there is shown a package 38 containing theintegrated circuit system 10. In the package 38, the substrate 12 ismounted on a heat dissipation plate 40 of a heat conductive material,such as a metal. The heat dissipation plate 40 has a plurality of heatdissipation fins 42. The substrate 12 is mounted on the heat dissipationplate 40 with the base 16 being seated on the top surface 41 of theplate 40 and secured thereto with a suitable bonding material 48. Acover 44 extends over the integrated circuit system 10 and beyond theouter edges of the integrated circuit system 10. A spacer ring 46 ismounted between the cover 44 and the substrate 12 of the integratedcircuit system 10. The spacer ring 46 is secured to both the cover 44and the body 14 of the integrated circuit system 10. The spacer ring 46is made of a material having a thermal coefficient of expansion betweenthat of the cover 44 and the body 14 of the integrated circuit system 10so as to prevent any breaking of the bond between the spacer ring 46 andthe cover 44 and the integrated circuit system 10. The cover 44 may beof a material having good heat conduction, or, preferably, may contain asuitable closed active cooling system, such as a flow of a suitablecooling medium. The substrate 12 of the integrated circuit system 10 islarger than the cover 44 so as to extend beyond the periphery of thecover 44. Various conductors 18 in the body 14 of the substrate 12extend to vias 20 adjacent the edges of the substrate 12. The vias 20extend to the top surface 22 of the body 14. Input and output terminals50 extend over the top surface 22 of the body 14 adjacent the edges ofthe body 14, and are mechanically and electrically connected to the vias20 by suitable terminal bumps 32. Thus, the integrated circuit system 10is hermetically sealed in the package 38 and is provided with dual heatdissipation means, the heat dissipation plate 40 and the cover 44. Theinput and output terminals 50 are electrically connected to the circuitin the IC piece 30 and to the power supply circuit chips 34 through theconductors 18 and the vias 20.

Thus, there is provided by the present invention an integrated circuitsystem which includes an IC semiconductor piece having thereon acircuit, such as a microprocessor, which includes a plurality offunctional blocks, each of which may use a separate and sometimesdifferent operational voltage. Also included are a plurality of powersupplies, such as DC-DC converters, each of which is electricallyconnected to a separate functional block on the IC piece so as to supplythe proper power to the particular functional block. The power suppliesare preferably mounted on a substrate of an insulating material on whichthe IC piece is also mounted. Each of the power supplies is electricallyconnected to its respective functional block on the IC piece throughconductors and vias in the substrate to which terminal pads or bumps onthe IC piece are connected, Alternatively, the power supply may beconnected directly, where appropriate, to the IC piece by suitableconnection technology. By having the power supplies connected directlyto the functional blocks, rather than to terminal pads around the edgeof the IC piece, the power bus widths are kept narrow and their lengthsare shorter, with acceptable power bus thickness, so as to save spaceand minimize resistive current loss and electrical noise. Also, thecommon signal ground on the IC piece takes minimal current, and can beof minimum width.

Some circuits require high dielectric constant, low voltage capacitors,and resistors and small inductors. In the system 10 of the presentinvention, such capacitors, resistors and inductors can be incorporatedin the dielectric body 14 of the substrate 12.

High dielectric constant capacitors embedded in a fired multilayerceramic printed circuit board stack on a metal support are known. Ascreen printable low firing temperature capacitor ink is formed fromlead-magnesium niobate and lead titanate powders, mixed together with aglass powder or a lead oxide powder, and a suitable organic vehicle. Thecapacitor layer is alternated with conductor layers, usually of silver,to form high dielectric constant capacitors.

Embedded resistors can also be made part of the present multilayerceramic system. Thick film resistors can be made from ruthenium oxideand suitable glasses that sinter at low temperatures, mixed with anorganic vehicle. The resistor ink can be screen printed onto a greentape stack on a metal support substrate and covered with one to twogreen tapes and terminated with an underlying first conductor layer. Thegreen tapes are aligned, laminated and fired. A second conductor layercan be screen printed on top of the fired, supported green tape stackand post-fired.

Inductors are made by screen printing a thick film conductor ink madefrom silver, preferably a mixture of silver powder and silver flake,together with a glass and an organic vehicle over a green tape.

In the device of the present invention, the capacitors, resistors andinductors can be positioned wherever desired on the substrate. Thisallows the capacitors and inductors to be properly positioned so as toeliminate coupling ground/power noise. If desired, the capacitors can beprovided on the power supply circuit chips 34, the signal processingpiece 30, or they can be discrete components that are placed in therecesses 24 in the body 14, or on the top surface of the body 14.Furthermore, in the substrate 12, signal lines can be built intransmission-line, shielded configuration to prevent undesirablecrosstalk.

The low voltage integrated circuit, such as the type that may be used inthe IC device of the present invention, may have to interact withexternal integrated circuits or systems that operate at voltages higherthan the operating voltage of the low voltage integrated circuit. Insuch case, voltage-translating interface circuitry is necessary so thatsignals can be transmitted from the chip operating at low voltage to anyothers operating at higher voltages. Since the power supply chipsutilize technology that converts a high voltage DC input to a lowvoltage input, unused portions of the chips can also be utilized toconstruct the interface circuitry to provide signal voltage translationbetween the low voltage chip and the other chips in the signal path. Insuch case, a one volt signal will go from the substrate to the voltagetranslation circuitry on a power supply chip using the metallization onthe substrate and then, after voltage translation, to an output pad onthe substrate. A high voltage input signal will follow a reverse butsimilar path.

Although the device of the present invention has been shown anddescribed as having the power supply chips and the interface circuits onseparate chips mounted on a substrate, the power supply circuits and theinterface circuit may be placed on a single silicon chip. In addition,the power supply circuitry, signal level translation interface circuitryand the signal processing circuitry may be fabricated on a singlesilicon substrate. Also, capacitors, resistors and inductors may beintegrated into, or fabricated on the surface of, the single siliconchip. Furthermore, the power supply circuits may be formed of smartpower supplies which go into “standby” when the function block is notbeing used.

What is claimed is:
 1. An integrated circuit system comprising: asubstrate of an insulating material having a surface; an ICsemiconductor piece mounted on said substrate surface, said IC pieceincluding an electrical circuit having a plurality of functional blocks;and a plurality of power supply chips mounted on said substrate, each ofsaid power supply chips being electrically connected to a separatefunctional block of said IC piece and being capable of reducing theinput voltage to a lower voltage required by the functional block of thecircuit to which the power supply chip is connected.
 2. The integratedcircuit system of claim 1 in which the substrate includes a plurality ofelectrical conductors extending therethrough, said power supply chipsand the IC piece being electrically connected to the conductors in thesubstrate to electrically connect the power supply chips to thefunctional blocks of the IC piece.
 3. The integrated circuit system ofclaim 2 in which the substrate comprises a body made from multiplelayers of insulating material, the conductors are deposited on each ofthe multiple layers and vias of a conductive material connect theconductors through the insulating layers to the surface of the body. 4.The integrated circuit system of claim 3 in which the IC semiconductorpiece has a plurality of contacts on a surface thereof with the contactsbeing seated on and engaging the vias in the substrate at the surface ofthe substrate, or a conductor on the surface of the substrate.
 5. Theintegrated circuit system of claim 4 in which the body of the substratehas a plurality of recesses in its top surface with conductors beingexposed in each recess, the power supply chips are seated in therecesses and are electrically connected to the conductors so as to beelectrically connected to the IC piece through the conductors and vias.6. The integrated circuit system of claim 3 in which the body of thesubstrate contains regions of a magnetic material with conductors in orsurrounding the magnetic material to form embedded inductors.
 7. Theintegrated circuit system of claim 6 in which capacitors are embedded inthe multiple insulating layers by screen printing a capacitor ink on aninsulating layer and screen printing a conductor ink above and below thecapacitor ink layer.
 8. The integrated circuit system of claim 2 inwhich a housing surrounds and encloses the IC piece and the substrate,the housing having heat conducting capabilities to cool the IC piece. 9.The integrated circuit system of claim 8 in which the housing includes aheat dissipating plate on which the substrate is mounted, said heatdissipation plate being of thermally conductive material and having finsextending therefrom.
 10. The integrated circuit system of claim 8 inwhich the housing further comprises a cover extending over the IC chipand having cooling means, and means to secure the cover to the substrateso as to enclose the IC piece between the cover and the substrate. 11.The integrated circuit system of claim 1 including capacitors on thesubstrate, IC piece and/or the power supply chip electrically connectedto the various circuits thereon.
 12. The integrated circuit system ofclaim 1 including inductors on the substrate, IC piece and/or the powersupply chips and electrically connected to the various circuits thereon.13. The integrated circuit system of claim 1 further including voltagefeedback means connected between the circuit on the IC piece and thepower supply chip.
 14. An integrated circuit system of claim 1 whereinthe plurality of power supply chips are formed as a single chip on asilicon substrate.
 15. The integrated circuit system of claim 14 whereinthe single silicon chip containing the multiple power supply chipsfurther containing I/O circuits of the said integrated circuit system.16. The integrated circuit system of claim 15 wherein the I/O circuitsare also capable of voltage level translation between the IC pieceoperating at low voltage and the external circuitry operating at ahigher voltage.
 17. The integrated circuit system of claim 1 whereinsections of the power supply chips may be combined and formed in acommon silicon chip and other sections are formed in separate chips. 18.The integrated circuit system of claim 2 wherein certain connectionsbetween the IC piece and the power supply chips may be made by directconnection without connecting through the substrate.
 19. An integratedcircuit system comprising: an IC semiconductor piece containing anelectrical circuit having a plurality of functional blocks; and aplurality of power supply circuit chips on said semiconductor piece,each of said power supply circuit chips connected to a separatefunctional block and being capable of reducing an input voltage to alower voltage required by the functional block of the circuit to whichthe power supply circuit chip is connected.